Mineral content of pastures selected by grazing dairy cows.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 19 MINERAL CONTENT OF PASTURES SELECTED BY GRAZING DAIRY COWS R. C. KELAWAYA, N. SRISKANDARAJAHB, R. TASSELLA, A. ANDREW.9 and E. HAVILAH *Department of Animal Science, University of Sydney, Camden, N.S.W. 2570. ` University of Western Sydney Hawkesbury, Richmond, N.S.W. 2753. CNSW Agriculture, Berry, N.S.W. 2535. C Mineral deficiencies in the diet can limit efficiency of milk production and reproduction. The aim of this study was to identify possible mineral deficiencies in pasture selected by cows on 3 dairy farms in south-eastern N.S.W. The pastures were predominantly ryegrass/clover from April-November and kikuyu/ paspalum from December-March. Fig. 1. Mineral content of pasture selected in relation to minimum Ca and P concentrations in the diet recommended for cows giving 10 (...), 20 (---) and 30 (-) litres milk/day (NRC 1988). Results in Fig. 1 show that concentrations of calcium and phosphorus in pasture selected frequently were suboptimal for milk production, on all 3 farms. Other mineral deficiencies identified were copper (throughout the year), magnesium (August-September) and sodium (January-March). The most economic strategies for correcting these mineral deficiencies currently are being investigated. NRC (1988). Nutrient Requirements of Dairy Cattle, 6th rev. ed. National Research Council: Washington, D.C. 385